The invention relates in general to wireless communication systems, and more specifically to managing pilot signal transmission in a wireless communication system.
Base stations in cellular communication systems provide communications services to wireless communication devices within geographical cells where each base station exchanges signals with wireless communication devices within an associated cell. The size and shape of each cell is determined by several factors and are at least partially based on design parameters of the base station. In addition to large macro cells that provide services to numerous devices within relatively large geographical areas, some cellular communication systems are increasingly employing smaller cells to increase efficiency, improve coverage, improve the quality of service, and provide additional services. The smaller cells may include a variety of sizes typically referred to as microcells, picocells and femtocells. Microcells and picocells are often implemented within office buildings, shopping centers and urban areas in order to provide additional security, higher user capacity for the area, additional service features, and/or improved quality of service. Femtocells have relatively smaller geographical areas and are typically implemented at residences or small office locations. Since typical cellular backhaul resources may not be available in these locations, femtocells are sometimes connected to the cellular infrastructure through DSL or cable modems. Femtocells are part of the cellular network and, therefore, communicate with the wireless devices using the same techniques as those used by macrocells. Accordingly, a femtocell base station must also broadcast a pilot signal to enable communications with wireless communication devices. Since femtocells serve only a limited number of authorized users, the transmission of pilot signals from the femtocells are likely to interfere with unauthorized wireless communication devices that are not operating on the particular femtocell. Interference due to pilot signals increases with the number of femtocells within an area.
Accordingly, there is a need to reduce interference caused by pilot signal transmissions from base stations serving overlapping or neighboring geographical areas.